In the prior art, devices such as electro-optic components are typically excited through wire connections to respective electrical contact areas of the electro-optic components. Because a connecting wire has inductance, a resonant electrical circuit is formed between the inductance of the connecting wire and the capacitance of the electro-optic device. This resonant electrical circuit limits the maximum useful electrical excitation frequency of the electro-optic device.
An electro-optic component is formed from a suitable electro-optic material and is typically provided with electrical contacts which are deposited on its surface for application of appropriate electrical modulation signals. The material of a typical electro-optic device has a comparatively high dielectric constant so that the device presents a high-capacitance load to an electrical excitation source. This high capacitance causes serious difficulties in communication of high-performance, i.e., high-frequency, signals to the electro-optic device.
This communication of electrical excitation signals to an electro-optic device is often made more difficult by the unusual physical configuration or construction of such devices, such as, for example, quadrapole and octapole structures.
The most common interconnection practice in the prior art for driving electro-optic devices and other types of devices is to use simple wire connections provided by interconnecting wires. Because each of the connecting wires has a series inductance, a series resonant electrical circuit is formed with the inductance of a connecting wire and the capacitance of the device. This series resonant electrical circuit limits the maximum useful electrical excitation frequency of the device. Even if the connecting wires are made as short as practical, some inductance is still present in the connecting wire. For example, if the total length of a connecting wire is nominally 1 cm. and is positioned near a ground plane, the inductance will be on the order 10 nH. Typical electro-optic elements have capacitances of several thousand picofarads. With several nanohenries of wire inductance and several thousand picofarads of device capacitance, a series resonance occurs at a frequency in the range of 10MHz to 100MHz. In general, a device with this type of connection is limited to operation below that resonant frequency.
For a device having relatively high capacitance to operate at higher frequencies, either the series resonance must be shifted to a frequency above the maximum frequency of interest, or the series resonances must simply be eliminated. The only way to shift a series resonance to a higher frequency is to decrease either the series inductance or the capacitance of an electro-optic device. Since the capacitance of the device is an inherent physical characteristic, it cannot be altered. In practice, the series inductance of a lead cannot be changed by more than a small amount because of the physical length required for the simple wire connection.
Consequently, a need exists for a technique to make a better connection for an electrical excitation signal to a device such as an electro-optic device in order to substantially eliminate or significantly reduce series resonance effects.